定义一个继承自div的对象
function Node()
{
}

如果使得Node继承自div对象
[解决办法]

 function Node(html){
 var el=document.createElement('Div');
 for(var k in  this) el[k]=this[k];
 el.innerHTML=html;
 return el;
 }
 Node.prototype.hide=function(){   //添加隐藏方法
 this.style.display="none"
 }
 var node=new Node( 'ok'  ) //实例 并且 HTML = ok
 document.body.appendChild( node   );
 setTimeout( function(){ 
  node.hide();  //隐藏
 },1500 )

[解决办法]
function mydiv(){
var div = document.createElement('div');
for(var p in this.constructor.prototype){
div[p] = this.constructor.prototype[p]
}
return div;
}
mydiv.prototype.kk = function(){alert('kk')}

var md = new mydiv();

md.kk();
//md is HTMLDIVelement
//md has kk function()